One or two load dumps can be used for a permanent magnet (PM) generator based wind turbine. If one load dump is used, it can be placed across the DC link or across the terminals of PM generator. If two load dumps are used, one can be placed across the DC link and another can be placed across the terminals of PM generator. In events of grid failure or converter failure, one or both load dumps can be used for a full scale converter based wind turbine.
For a full scale converter based wind turbine with two load dumps, the first load dump connected to the output terminals of the generator may be rated about 1-2 times of the second load dump connected across the DC link. The ratings of the load dumps are based on the power dissipation capacity. For higher power (e.g. 6-15 MW) wind turbines, a significantly bigger load dump might be required at the generator output terminals and across the DC link terminals. Hence, there may be a significant increase in cost, weight and size/space required for the load dumps with the increase in turbine power.